1. How does light
travel and interact
with matter?
Chapter 12: Lesson 3:

2. Distance traveled by light from sun to
earth
=90 million miles

3. What is light made up of?
Electric waves Magnetic waves

4. Light can travel through vacuum.
Speed of light in vacuum is faster than
its speed in solid, liquid or gas.

5. Distance between one peak
and the next in a wave.
To calculate the speed of a wave:
Speed = Wavelength x frequency

6. Types of materials
Transparent
Translucent
Opaque
Allow most light to
pass through them.
Allow some light to
pass through them.
No light can pass
through them.

7. Determine what is
transparent, translucent and opaque.

8. When light does not pass through
opaque objects it forms SHADOWS.

9. Position of the SHADOW depends upon
the position of the light source.
Example:

10. Draw the sunlight rays falling on the
objects.

11. Determine
the
position of
the sun in
the
following
pictures.

14. To change the size of the shadow, move
closer or away from the light source.

15. How do we see objects?
Light hits the objects and scatters (we
see objects).

16. Law of reflection:
Angle of incoming light = angle of
reflected light

17. How can we see images in mirrors?

19. Draw the
light
rays that
helps
the girl
see her
image.

20. The image in a mirror is clear because
most of the light is reflected off the
mirror’s smooth surface.

21. Look at the spoon in the glass of water.
Is the spoon broken?

22. The spoon is not broken.
When light enters a different medium it
bends and when it is leaving it bends to the
opposite side again.

23. Bending of light while passing from on
substance to another is called
REFRACTION.

25. Draw the light rays to explain what is
happening.

26. WaterAir Air
Draw the light rays to explain what is
Refraction.

27. Sunlight is
white light,
when it
passes
through a
rain drop it
is divided
into 7
colors.

28. When white light passes through a prism it
comes out as a spectrum (7 colors of
rainbow)

29. The colors of the spectrum.

30. Each color has a different wavelength.

31. Red light has long wavelength.
Violet light has Short wavelength.
The way we see colored objects
depends on the color that is reflected.

32. Example:
The leaf is green so it absorbs all light
and green light is reflected.

33. The apple is red so it absorbs all light
and red light is reflected.

34. Predict what light is reflected for you to
see the color.